Tumor niche network-defined subtypes predict immunotherapy response of esophageal squamous cell cancer.

Despite the promising outcomes of immune checkpoint inhibitors (ICIs), resistance to ICI presents a new challenge. Therefore, selecting patients for specific ICI applications is crucial for maximizing therapeutic efficacy. Herein, we curated 69 human esophageal squamous cell cancer (ESCC) patients' tumor microenvironment (TME) single-cell transcriptomic datasets to subtype ESCC. Integrative analyses of the cellular network and transcriptional signatures of T cells and myeloid cells define distinct ESCC subtypes characterized by T cell exhaustion, and interleukin (IL) and interferon (IFN) signaling. Furthermore, this approach classifies ESCC patients into ICI responders and non-responders, as validated by whole tumor transcriptomes and liquid biopsy-based single-cell transcriptomes of anti-PD-1 ICI responders and non-responders. Our study stratifies ESCC patients based on TME transcriptional network, providing novel insights into tumor niche remodeling and potentially predicting ICI responses in ESCC patients.

Cancer-Associated Fibroblasts in Esophageal Cancer.

Cancer-associated fibroblasts (CAFs), a heterogenous population, can promote cancer cell proliferation, migration, invasion, immunosuppression, and therapeutic resistance in solid tumors. These effects are mediated through secretion of cytokines and growth factors, remodeling of the extracellular matrix, and providing metabolic support for cancer cells. The presence of CAFs in esophageal carcinoma are associated with reduced overall survival and increased resistance to chemotherapy and radiotherapy; thus, identifying therapeutic vulnerabilities of CAFs is a necessity. In esophageal cancer, the mechanisms for CAF recruitment, CAF-mediated promotion of tumorigenesis, metastatic dissemination, and therapeutic resistance have yet to be fully evaluated. Here, we provide an overview of the current understanding of CAFs in esophageal cancer, namely in esophageal squamous cell carcinoma and esophageal adenocarcinoma, as well as in the preneoplastic conditions that predispose to these cancers. Interestingly, there is a discrepancy in our knowledge of CAF biology between esophageal cancer subtypes, with very few studies in esophageal adenocarcinoma, and its precursor lesion Barrett's esophagus, compared with esophageal squamous cell carcinoma. We propose that although great strides have been made, certain questions remain to which answers hopefully will emerge to have an impact on biomarker diagnostics and translational therapeutics.

p53 Gain-of-Function Mutation Induces Metastasis via BRD4-Dependent CSF-1 Expression.

TP53 mutations are frequent in esophageal squamous cell carcinoma (ESCC) and other SCCs and are associated with a proclivity for metastasis. Here, we report that colony-stimulating factor-1 (CSF-1) expression is upregulated significantly in a p53-R172H-dependent manner in metastatic lung lesions of ESCC. The p53-R172H-dependent CSF-1 signaling, through its cognate receptor CSF-1R, increases tumor cell invasion and lung metastasis, which in turn is mediated in part through Stat3 phosphorylation and epithelial-to-mesenchymal transition (EMT). In Trp53R172H tumor cells, p53 occupies the Csf-1 promoter. The Csf-1 locus is enriched with histone 3 lysine 27 acetylation (H3K27ac), which is likely permissive for fostering an interaction between bromodomain-containing domain 4 (BRD4) and p53-R172H to regulate Csf-1 transcription. Inhibition of BRD4 not only reduces tumor invasion and lung metastasis but also reduces circulating CSF-1 levels. Overall, our results establish a novel p53-R172H-dependent BRD4-CSF-1 axis that promotes ESCC lung metastasis and suggest avenues for therapeutic strategies for this difficult-to-treat disease. SIGNIFICANCE: The invasion-metastasis cascade is a recalcitrant barrier to effective cancer therapy. We establish that the p53-R172H-dependent BRD4-CSF-1 axis is a mediator of prometastatic properties, correlates with patient survival and tumor stages, and its inhibition significantly reduces tumor cell invasion and lung metastasis. This axis can be exploited for therapeutic advantage. This article is featured in Selected Articles from This Issue, p. 2489.

Key Genetic Determinants Driving Esophageal Squamous Cell Carcinoma Initiation and Immune Evasion.

BACKGROUND & AIMS: Despite recent progress in identifying aberrant genetic and epigenetic alterations in esophageal squamous cell carcinoma (ESCC), the mechanism of ESCC initiation remains unknown. METHODS: Using CRISPR/Cas 9-based genetic ablation, we targeted 9 genes (TP53, CDKN2A, NOTCH1, NOTCH3, KMT2D, KMT2C, FAT1, FAT4, and AJUBA) in murine esophageal organoids. Transcriptomic phenotypes of organoids and chemokine released by organoids were analyzed by single-cell RNA sequencing. Tumorigenicity and immune evasion of organoids were monitored by allograft transplantation. Human ESCC single-cell RNA sequencing data sets were analyzed to classify patients and find subsets relevant to organoid models and immune evasion. RESULTS: We established 32 genetically engineered esophageal organoids and identified key genetic determinants that drive ESCC initiation. A single-cell transcriptomic analysis uncovered that Trp53, Cdkn2a, and Notch1 (PCN) triple-knockout induces neoplastic features of ESCC by generating cell lineage heterogeneity and high cell plasticity. PCN knockout also generates an immunosuppressive niche enriched with exhausted T cells and M2 macrophages via the CCL2-CCR2 axis. Mechanistically, CDKN2A inactivation transactivates CCL2 via nuclear factor-κB. Moreover, comparative single-cell transcriptomic analyses stratified patients with ESCC and identified a specific subtype recapitulating the PCN-type ESCC signatures, including the high expression of CCL2 and CD274/PD-L1. CONCLUSIONS: Our study unveils that loss of TP53, CDKN2A, and NOTCH1 induces esophageal neoplasia and immune evasion for ESCC initiation and proposes the CCL2 blockade as a viable option for targeting PCN-type ESCC.

Tumor-Derived CCL5 Recruits Cancer-Associated Fibroblasts and Promotes Tumor Cell Proliferation in Esophageal Squamous Cell Carcinoma.

Cancer-associated fibroblasts (CAF) can promote tumor growth, metastasis, and therapeutic resistance in esophageal squamous cell carcinoma (ESCC), but the mechanisms of action remain elusive. Our objective was to identify secreted factor(s) that mediate the communication between CAFs and ESCC tumor cells with the aim of identifying potential druggable targets. Through unbiased cytokine arrays, we have identified CC motif chemokine ligand 5 (CCL5) as a secreted factor that is increased upon co-culture of ESCC cells and CAFs, which we replicated in esophageal adenocarcinoma (EAC) with CAFs. Loss of tumor-cell-derived CCL5 reduces ESCC cell proliferation in vitro and in vivo and we propose this is mediated, in part, by a reduction in ERK1/2 signaling. Loss of tumor-derived CCL5 reduces the percentage of CAFs recruited to xenograft tumors in vivo. CCL5 is a ligand for the CC motif receptor 5 (CCR5), for which a clinically approved inhibitor exists, namely Maraviroc. Maraviroc treatment reduced tumor volume, CAF recruitment, and ERK1/2 signaling in vivo, thus, mimicking the effects observed with genetic loss of CCL5. High CCL5 or CCR5 expression is associated with worse prognosis in low-grade esophageal carcinomas. IMPLICATIONS: These data highlight the role of CCL5 in tumorigenesis and the therapeutic potential of targeting the CCL5-CCR5 axis in ESCC.

Tumor Niche Network-Defined Subtypes Predict Immunotherapy Response of Esophageal Squamous Cell Cancer.

Despite the promising outcomes of immune checkpoint blockade (ICB), resistance to ICB presents a new challenge. Therefore, selecting patients for specific ICB applications is crucial for maximizing therapeutic efficacy. Herein we curated 69 human esophageal squamous cell cancer (ESCC) patients' tumor microenvironment (TME) single-cell transcriptomic datasets to subtype ESCC. Integrative analyses of the cellular network transcriptional signatures of T cells, myeloid cells, and fibroblasts define distinct ESCC subtypes characterized by T cell exhaustion, Interferon (IFN) a/b signaling, TIGIT enrichment, and specific marker genes. Furthermore, this approach classifies ESCC patients into ICB responders and non-responders, as validated by liquid biopsy single-cell transcriptomics. Our study stratifies ESCC patients based on TME transcriptional network, providing novel insights into tumor niche remodeling and predicting ICB responses in ESCC patients.